A refrigerant apparatus which has an injection passage through which the gas coolant within the gas-liquid separator is injected into the compressor has been known as a so-called gas injection type refrigerant apparatus. FIG. 10 shows one type of such a conventional gas injection type refrigerant apparatus. The compressor 400 used for this type of refrigerant apparatus is a rotary type compressor which has a compression chamber, the effective volume of which is varied according with the rotation of the rotor. However, since both the coolant within the gas portion of the gas liquid separator 5 and the coolant within the evaporator 8 are introduced into the same compression chamber of the compressor 400, it is very hard to work the compressor 400 effectively. Therefore, the refrigerant apparatus shown in FIG. 10 is deemed to be impossible to work effectively.
In order to suck the gas coolant within the gas-liquid separator effectively, the refrigerant apparatus shown in FIG. 11 has also been used. Such an apparatus as shown in FIG. 11 has a main compressor 400 to which the coolant within the evaporator 8 is introduced and a sub-compressor 200 to which the coolant within the gas fuel separator 5 is introduced. The refrigerant apparatus shown in FIG. 11, however, has a serious disadvantage in that the sub-compressor 200 requires an extra lubricant system. The main compressor 400 used for the refrigerant apparatus is lubricated by the lubricant which is introduced into the compressor with the coolant. On the other hand, since the sub-compressor 200 is connected with the gas portion of the gas-liquid separator, the lubricant within the refrigerant apparatus is very hard to introduce into the sub-compressor 200. Therefore, the sub-compressor 200 requires an extra lubricating system in order to lubricate itself.